Improvement in cut-off gear for steam-engines



etchedtate @met @imita JOH'NVB. ROOT, OF -NEVW YORK, N.A Y.

Letters Patent No. 95,838, dated October 12, 1869; antedated October 2, 1869.

IMPROVEMENT IN CUT-OPI' GEAR FOR STEAM-ENGINES.

The Schedule referred to in these Letters Patent and makngpaxt of the same.

l.exact description, `reference being had to the accompanying drawing, forming part of this specication,

and in which- Figure lrrepresents a plan of my improved out-oii gear, and

Figure 2, a side elevation of the same in its connection (asshown by red lines) with the-governor of an engine.

Similar letters of parts.

My invention consists in so gearing the drivingpulley of the governor with the mainshaft of the enreference indicate corresponding gine, or driving said pulley through motion derived from said shaft, as that a variablevelocity is given to the governor during each stroke of the engine, in such manner as that the 'minimum speed of the governor takes place at the commencement of each stroke of the engine, or thereabouts, whereby the valve operated by the governor is made to open wide for the free admission of steam at the commencement of each stroke of the engine, and to cut it oli, or lessen the admission, as the stroke progresses, without impairing or destroying the general action of the governor as a regulator of speed.

Referring to the accompanying drawing- A represents the main shaft of an ordinary reciprocating engine, and

B, the driving-crank thereof. A C is the pulley, fast to a countershaft, D, for driving the governor.

Any suitable governor having a quick or sensitive action, such as those in which springs, in combination with balls or weights, are used, and any suitable Y regulating-valve under control of said governor, may

be adopted.

E and F are double-scroll gear-wheels, the one, E, being fast on the main shaft A, and the other, F, fast on the countershaft I), or otherwise connected with the governor-driving pulley C.

The toothed scrolls a b and c d of these wheels are so pitched or set, relatively to the crank B, or stroke of the piston, as that, supposing the crankshaft to be travellingin the direction indicated by the arrow x, in iig. 2, the shortest radius of the scroll a will fall into -gear with the scroll o, at its longest radinsat the commencement of one stroke of the engine, and a like action of the scrolls b andd take place at the commencement of the return-stroke of the piston'.

This gives a minimum velocity in a fixed or positive manner to the governor, at or about the commenoement of' each stroke of the engine-piston, and

thereby causes the governor to establish a full or free admission of steam at such points in the stroke; but after the piston has commenced its stroke in either direction, and as said piston progresses in its stroke, a quicker or accelerating velocity, by the action of the scrolls a c, or b (l, is communicated to the governor-driving pulley O, and of a consequence to the governor, thereby causing the latter to so operate the regulating-valve controlled by it as to cause said valve to diminish or cut oii the. admission of steam to the engine during or toward the close ofthe pistou-stroke.

By the action of the scrolls a l1 and c d, it will be seen that the minimum Velocity' of the governor, at the commencement of each piston-stroke, is eliected suddenly, thus securing, in a prompt manner, a full admission of steam at the beginning of the stroke.

Such action in no way impairs or destroys the geni eral action of the governor as a regulator of speed, but any tendency to increase 01 diminish beyond the given or required velocity is promptly checked by the action ofthe governor on there'gulating-valve, but on running the exigirle, faster or slower, the position of said valve is necessarily changed, and consequently the action of the cut-ofi' gear hereinbefore described altered to cut oil` earlier or later in the stroke, thus establishing a variable cut-ofi` under control of the governor, the regulating-valve being kept in constant motion, by the action of the scrolls a b and c ll, to eiiect free admission and cut off of the steam, irrespective ofthe speed of the engine, or, rather, at all velocities of the latter, only varying the period of cut-off, which may be fixed at a ce1'- tain point in the stroke for a given. speed, by a suitable set of the regulating-valve.

' That is here claimed, and desired to be secured by Letters Patent, is-

l. The combination or gear of the driving-pulley of the governor with the main shaft of the engine, in such manner as that a reduced and minimum velocity is imparted to the governor at or about the commencement of each piston-stroke of the engine, at all speeds of-the latter, substantially as specified.

2. The combination, with the main or crank-shaft A, of the engine and governor-.driving pulley O, of the double-scroll gears E and F, essentially as herein set orth. i

JOHN B. ROOT. "Witnesses:

J. W. Goonies, Faun. HAYNEs. 

